Good luck .. Im sure you will do well.

Prepare your swim bag the day before ... rinse your costume on you in the shower and take off there ... or even plan on showering there and put dry clothes on ... wouldnt this reduce the effort some? ... eh, what would I know? :)

I doubt your gym room will be full of fit young things. Think a mixed group many of whom will be as wobbly as you - in all ways ...:P